JP3473453B2 - Circuit breaker fluid pressure drive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a configuration of a fluid pressure drive device for opening and closing contacts of a power circuit breaker. 2. Description of the Related Art A power circuit breaker provided to protect a power supply system in the event of an emergency such as a lightning strike requires an extremely high speed opening / closing operation. Must. For this reason, a high pressure is always applied to the smaller pressure receiving area of the fluid pressure cylinder that opens and closes the contact, and the larger pressure receiving area is used as an operation room at a high pressure or a low pressure to close or open the circuit. The main valve for operating this fluid pressure cylinder requires a very large flow rate. As a conventional main valve, for example, as described in JP-A-6-338241, an open-circuit main valve and a close-circuit main valve for operating the open-circuit main valve are provided separately from the open-circuit main valve and the close-circuit main valve. A configuration has been adopted in which a closing valve that operates the valve is driven by a switching valve that is integrally formed, and this switching valve is switched by a pilot valve for opening and closing. Further, as a configuration of the switching valve and the pilot valve, for example, as described in JP-A-55-53821, a supply pressure is always applied to one end of the switching valve and a pilot chamber is provided at the other end. A secondary side of the pilot valve for closing, the primary side of which is connected to the supply side;
A configuration is adopted in which the primary side of the closing pilot valve whose secondary side is connected to the return side is connected. In the first prior art configuration, the valve body of the opening main valve is formed in a hollow shape and communicates with the secondary side of the opening main valve connecting the inside to the return side. Therefore, there is a problem that the opening amount of the valve tends to fluctuate under the influence of pressure fluctuation or the like when a large flow rate flows during opening. Further, since the supply pressure is always applied to the entire primary side of the valve body of the closing main valve and the pilot chamber is provided on the opposite side, the inner side of the valve seat from the valve seat during the opening operation to the open state. There is also a problem that the force due to the supply pressure acting on the entire portion acts on the valve seat to generate a large stress, so that the valve seat is easily damaged. Further, the closing main valve needs to have a larger pilot chamber diameter than the valve seat diameter. However, since the above-mentioned prior art valve body has an integral structure, the valve body or the casing is divided and manufactured and then integrated. And it was difficult to manufacture. On the other hand, in the configuration of the second prior art, since the fluid is supplied to and discharged from the pilot chamber corresponding to the diameter of the valve body of the switching valve, there is a problem that the pilot valve becomes large for both open and closed circuits. was there. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems in the prior art, to reduce the size and facilitate manufacture, to obtain stable characteristics, and to achieve high reliability in a fluid for a circuit breaker. An object of the present invention is to provide a pressure driving device. In order to achieve the above object, according to the present invention, a low-pressure chamber, which is always connected to the return side, is provided on the back surface of the valve body of the main valve for opening in the same direction as the pilot chamber. . As a result, the pilot flow rate for operating the opening main valve is reduced, and the switching valve can be miniaturized. The amount is less likely to fluctuate, and stable characteristics can be obtained. Next, an auxiliary chamber connected to the operation chamber of the fluid pressure cylinder is provided on the back of the valve body of the closing main valve. Thus, the pressure in the auxiliary chamber is low during the opening operation to the open state, so that the force acting on the valve seat is reduced, and damage to the valve seat can be eliminated. Further, the closing main valve comprises a valve body for opening and closing between the cylinder operating chamber and the supply side, and a piston for pushing and opening the valve body by receiving a pilot operation force, and a back surface of the piston. The first spring is provided on the back surface of the valve body with the second spring facing the first spring and applying a larger force than the first spring. Thus, the valve body and the piston can be manufactured separately and incorporated as they are, which facilitates the manufacture. Further, the switching valve has a smaller diameter than the valve seat and a rear surface on the side opposite to the valve seat of the closing valve that opens and closes between the control port connected to the pilot chamber of the opening main valve and the pilot chamber of the closing main valve and the supply side. An open cylindrical portion is provided on the return side, and a switching valve pilot chamber for switching this switching valve is provided on the side opposite to the valve seat that opens and closes between the control port and the return side. The area is made larger than the area of the difference between the valve seat diameter of the closing valve and the diameter of the cylindrical portion. Thus, the pilot flow rate for operating the switching valve can be reduced, and the pilot valve can be downsized. Therefore, according to the present invention, it is possible to realize a fluid pressure drive device of a circuit breaker which can be downsized and easily manufactured, has stable characteristics, and has high reliability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the circuit breaker fluid pressure driving device according to the present invention will be described below with reference to FIGS. FIG. 1 shows a closed state (a state in which electricity is supplied), and FIG.
3 shows a state during an open circuit operation, FIG. 3 shows an open state (disconnected state), FIG. 4 shows an initial state during a close operation, and FIG. 5 shows a late state during a close operation. A fluid pressure driving device 3 for a circuit breaker, which comprises a fixed contact 1 and a movable contact 2 and opens and closes contacts, comprises a fluid pressure cylinder 4 for driving the movable contact 2 with a piston 5. The supply pressure of the working fluid discharged from the fluid pressure source 8 and accumulated in the accumulator 9 always acts on the small pressure receiving area side 6, and the large pressure receiving area side forming the cylinder operating chamber 7 is connected to the open main valve 11 and the closed circuit. The main valve 12 is selectively connected to a high pressure supply pressure side or a low pressure return side connected to the reservoir 10. The opening main valve 11 is a two-way valve for connecting the cylinder operating chamber 7 to the low-pressure return side to open the circuit. The control port 14 of the switching valve 13 is connected to the opening main valve pilot chamber 17, and the valve body 15 is closed by the force of the spring 16 and the force acting when the opening main valve pilot chamber 17 is set to a high pressure. Open circuit main valve pilot chamber 17
Is opened by the pressure of the fluid extruded from the cylinder operation chamber 7 when the pressure is lowered. A low-pressure chamber 18 is provided on the back surface of the valve body 15 and always has a low pressure through the return side. The inner diameter of the opening main valve pilot chamber 17 is smaller than that of the valve seat 19 by that amount. However, the force for closing the valve by the supply pressure applied to the main valve pilot chamber 17 for opening is greater than the force for opening the valve by the supply pressure acting outward from the valve seat 19 in the closed state. It is configured as follows. The closing main valve 12 is a two-way valve for connecting the cylinder operating chamber 7 to a high pressure supply side to perform a closing operation, and has a valve body 20 and a piston 21. The force of the spring 22 is acting on the valve body 20 and the force of the spring 23 is acting on the piston 21, and the spring 22 generates a greater force than the spring 23. The control port 14 of the switching valve 13 is connected to the closing main valve pilot chamber 24 in the same manner as the opening main valve pilot chamber 17.
An auxiliary chamber 26 is provided which is connected to a valve chamber connected to the cylinder operation chamber 7 through the auxiliary chamber 26. The diameter of the valve seat 27 is smaller than the inner diameter of the closing main valve pilot chamber 24, that is, the outer diameter of the piston 21, and larger than the inner diameter of the auxiliary chamber 26. Therefore, the valve element 20 is provided with the closing main valve pilot chamber 2.
If the pressure is set to a low pressure, the difference between the force of the spring 22 and the force of the spring 23, the force of the supply pressure acting on the portion of the valve seat 27 and the auxiliary chamber 26 having a diameter difference, and the force of the pressure acting on the auxiliary chamber 26 If the closed main valve pilot chamber 24 is set to a high pressure, it is opened by the force generated here. The switching valve 13 connects the switching valve pilot chamber 28 with an open circuit pilot valve 37 and a close circuit pilot valve 39.
By selectively switching between high pressure and low pressure, the control port 14 communicating with the open main valve pilot chamber 17 and the close main valve pilot chamber 24 is connected to the supply side valve chamber 29 connected to the high pressure supply side or the low pressure return. It is a two-position three-way valve connected to one of the return valve chambers 30 connected to the side. The cylindrical portion 32 of the valve element 31 has a smaller diameter than the supply side valve seat 33 and the back surface of the cylindrical portion 32 is opened to the return side. The pressure receiving area of the switching valve pilot chamber 28 is equal to the return side valve seat 34 and the cylindrical portion 3.
It is configured to be larger than the pressure receiving area of the portion having the diameter difference of 2. Further, the switching valve pilot chamber 28 is
Is connected to a valve chamber having a control port 14. A holding mechanism 36 is provided on the back surface of the cylindrical portion 32 of the switching valve 31. This mechanism is for mechanically holding the valve element 31 when there is no fluid pressure, and has a holding force that does not affect the normal operation by the fluid pressure. The open-circuit pilot valve 37 and the close-circuit pilot valve 39 are both two-way valves configured to open when the open-circuit solenoid 38 or the close-circuit solenoid 40 is excited, and to be closed by the spring force when the excitation is released. Check valve 4
1 are connected in series. Closing pilot valve 3
9 is connected to the high pressure supply side,
Is connected to the primary side of the opening pilot valve 37 and the switching valve pilot chamber 28 via the check valve 41, and the secondary side of the opening pilot valve 37 is connected to the low pressure return side. Further, an anti-pumping piston 42 and a spring 43 are provided on the back surface of the check valve 41.
Is always located in the room leading to the low pressure return. Also,
A throttle 45 and a throttle 4 are provided on the secondary side of the closing pilot valve 39.
A conduit is provided through 6 to the return side, and the space between the throttle 45 and the throttle 46 is connected to the anti-pumping piston operation chamber 44. Therefore, the anti-pumping piston 42
The check valve 41 is closed by the pressure acting on the operation chamber 44, and is opened by the force of the spring 43. Next, the operation of this embodiment will be described. With the above configuration, in the closed state shown in FIG.
Cylinder operation chamber 7, main valve pilot chamber 17 for opening and main valve pilot chamber 24 for closing, switching valve pilot chamber 28, primary side of pilot valve 37 for opening and pilot valve 39 for closing, secondary of check valve 41 All sides are at high pressure and all valves are closed. When an open command is issued in this state, as shown by an arrow in FIG. 2, the open solenoid 38 is excited, the open pilot valve 37 is pushed open, and the switching valve pilot chamber 28 is returned to the low pressure return side. Connected to
The switching valve 13 is switched to the open state by the high pressure acting on the valve chamber having the supply side valve chamber 29 and the control port 14.
Accordingly, since the control port 14 and the opening main valve pilot chamber 17 connected thereto are connected to the return side to have a low pressure, the opening main valve 11 is opened by the high pressure acting from the cylinder operating chamber 7 of the fluid pressure cylinder 4. Cylinder operating room 7
Is connected to the return side, and the piston 5 and the movable contact 2 start the opening operation. After that, the small pressure receiving area side 6 of the cylinder 4
When the fluid in the cylinder operating chamber 7 is extruded by the high pressure, the main valve 11 for opening is kept open by the pressure difference generated before and after the main valve 11 for opening, and reaches the open state shown in FIG. . When the opening operation is completed, the flow from the cylinder operation chamber 7 to the return side stops, so that the pressure difference between the front and rear of the opening main valve 11 disappears.
Closed by On the other hand, since the excitation of the opening solenoid 38 is released, the opening pilot valve 37 is also closed by the spring force, and all the valves are again closed. At this time, the switching valve pilot chamber 28 is connected to the already low pressure control port 14 through the throttle 35, so that the switching valve 13 is maintained at a low pressure even when the open pilot valve 37 is closed. Maintain the open operation state. Since the pressure of the closing main valve pilot chamber 24 becomes low together with that of the opening main valve pilot chamber 17, the piston 21 of the closing main valve 12 once moves upward, and when the opening operation ends, the spring 23 moves downward. Returning, the closing main valve 12 is closed from the beginning and remains closed even if only the piston 21 moves, so that the above-described opening operation is not affected. Next, when a closing command is issued in the open state shown in FIG. 3, as shown in FIG.
0 is excited, and the closing pilot valve 39 is pushed and opened to flow from the primary side connected to the supply side to the secondary side, and the check valve 41 is pushed open to set the switching valve pilot chamber 28 to a high pressure. To switch the switching valve 13 to the closing operation state. Accordingly, the control port 14 and the closing main valve pilot chamber 24 connected thereto have a high pressure, so that the piston 21 and the valve body 20 of the closing main valve 12 move downward to open the valve, and the cylinder operating chamber 7 Piston 5 and movable contact 2
Starts the closing operation. As the pressure in the cylinder operation chamber 7 increases, the pressure in the auxiliary chamber 26 also increases through the conduction hole 25.
While the piston 5 is moving, it does not rise to the supply pressure.
That is, the pressure sufficient to drive the piston 5 by overcoming the load such as the supply pressure acting on the small pressure receiving area side 6, the mass of the movable contact, and the frictional force of the packing around the piston 5 is sufficient. This pressure is generally determined by the ratio of the pressure receiving area of the small pressure receiving area 6 to the pressure receiving area of the cylinder operating chamber 7. However, since the pressure receiving area of the cylinder operating chamber 7 is larger, this pressure is lower than the supply pressure. Accordingly, at this pressure, the piston 21 is pushed downward by the supply pressure acting on the closing main valve pilot chamber 24 and the force of the spring 23, and this force is greater than the force acting upward from the auxiliary chamber 26 and the spring 22. It is configured to be large. Therefore, during the closing operation of the piston 5, the closing main valve 12 is kept open, and the closing operation is continued. At this time, when the switching valve 13 is switched to the closing operation state, the opening main valve pilot chamber 17 also becomes high pressure.
The opening main valve 11 is closed before the start of the operation, and does not affect the operation at all because the force for closing the valve only increases. On the other hand, as shown in FIG. 5, when the closing pilot valve 39 is opened and the secondary side has a high pressure, the pressure in the anti-pumping piston operation chamber 44 increases to the pressure determined by the throttles 45 and 46. The pumping piston 42 overcomes the force of the high pressure on the secondary side of the check valve 41 and moves to the left to push the check valve 41 closed. However, since the switching valve 13 has already been switched to the closing operation state and the valve chamber having the control port 14 is at a high pressure, the restriction 3
The switching valve pilot chamber 28 connected here via 5 is maintained at a high pressure even when the check valve 41 is closed, and maintains a closed circuit operation state. Similarly, even when the excitation of the closing solenoid 40 is released and the closing pilot valve 39 is closed, the switching valve 13 maintains the closing operation state. When the closing operation is completed and the piston 5 stops and the flow stops, the cylinder operation chamber 7 and the communication hole 2
5. Since the auxiliary chamber 26 increases to the supply pressure, the valve body 20 and the piston 21 are pushed up and closed by the force of the spring 22.
When the closing pilot valve 39 and the check valve 41 are closed, the pressure between them closes through the throttles 45 and 46 and returns to the return side. Returned to As a result of these series of operations, the closed state shown in FIG. 1 is reached. According to this embodiment, the following effects can be obtained. First, since the circuit breaker requires an extremely high speed opening operation, the opening main valve 11 needs to flow an extremely large flow rate, and the diameter of the valve seat 19 and the opening amount of the valve body 15 become large. The pilot flow for operating this also increases. However, according to the present embodiment, the inner diameter of the opening main valve pilot chamber 17 is made smaller than that of the valve seat 19 by providing the low pressure chamber 18 on the back surface of the valve body 15 of the opening main valve 11, and the open state is established in the closed state. The force to close the valve due to the supply pressure applied to the main valve pilot chamber 17 overcomes the force to open the valve due to the supply pressure acting outward from the valve seat 19, and has a size sufficient to prevent leakage from the valve seat 19. Therefore, the pilot flow rate supplied to and discharged from the open-circuit main valve pilot chamber 17 can be reduced, and the switching valve 13 can be a small valve. Further, since the switching valve 13 also has a configuration in which the back surface of the cylindrical portion 32 of the valve element 31 is opened to the return side, the switching valve pilot chamber 28 has a smaller area than the area of the diameter difference between the return side valve seat 34 and the cylindrical portion 32. The pilot flow rate for operating the switching valve may be small because the pressure receiving area may be large.
7 and the closing pilot valve 39 can also be miniaturized. In this way, the entire hydraulic drive device can be downsized. In addition, the low-pressure chamber 18 is connected to the return side in a place where it is hardly affected by the flow of a large flow rate flowing out of the main valve 11 for opening when the circuit is opened. There is no variation in the opening amount and variation in the characteristics. Further, the back surface of the cylindrical portion 32 of the switching valve 13 is opened to the return side, and the holding mechanism 36 can be provided at this portion. Therefore, the fluid pressure source 8 is stopped and the accumulator 9 is stopped.
Even when pressure is not accumulated, the position of the valve body 31 is mechanically held, and when the operation is resumed after carrying out work such as transportation, installation, and inspection, the circuit breaker is kept in the same state as before the work. Work safety is increased. In the case of a two-position three-way valve such as the switching valve 13, it is necessary to manage the coaxiality of the opening and closing valves.
When the main valve for flowing a large flow rate has this configuration, it is difficult to obtain high accuracy because of its large size, and it becomes difficult to manufacture the main valve.
On the other hand, since the switching valve 13 is small, it is easy to realize high accuracy. Therefore, in the present embodiment, the main valve for opening 11 and the main valve for closing 12 are configured separately, and the main valve for closing 12 also includes the valve body 20 and the piston 21 as separate bodies. Accuracy control such as coaxiality at the time of processing becomes easy, and production becomes easy. Next, when the opening main valve 11 is closed after the opening operation, the pressure around the entire area becomes low, and the valve element 15 is seated on the valve seat 19 by the force of the spring 16. Closing main valve 1
In the case of the valve 2 as well, when the valve is closed after completing the closing operation, the surroundings are all at the supply pressure, and the valve element 20 is seated on the valve seat 27 by the force of the spring 22. Therefore, since the force at the time of seating is small as compared with the configuration in which the valve seat is closed by fluid pressure, damage to the valve seat can be prevented, a long life can be obtained, and high reliability is maintained for a long time. Moreover, these valves act in the opposite way to their intended function,
That is, when the main valve for opening 11 is in the closing operation, and the main valve for closing 12 is in the opening operation, the force due to the fluid pressure acts in the direction to close each valve. Is firmly closed and held, and even if it is not completely closed only by the spring force, it is securely closed by the fluid pressure, so that leakage from the valve seat can be more reliably prevented. . Open circuit pilot valve 37,
After the closing pilot valve 39 and the check valve 41 are also opened and a predetermined operation is performed, the surroundings have the same pressure and are closed by a spring force, and the opening pilot valve 37 is closed during the closing operation. After the closing operation, the pilot valve 39 and the check valve 41 are each more firmly closed by the fluid pressure, so that the valve seat can be prevented from being damaged similarly to the opening main valve 11 and the closing main valve 12. Leakage hardly occurs and high reliability is obtained. The low-pressure chamber 18 of the main valve 11 for opening and the auxiliary chamber 26 of the main valve 12 for closing also have the following effects. That is, in the opening main valve 11, the low pressure chamber 18 is provided to reduce the diameter of the opening main valve pilot chamber 17 so that the force required to close the valve during the closing operation is minimized. Since no excessive stress acts on the valve 19, damage to the valve seat can be prevented. On the other hand, in the closing main valve 12, the pressure of the auxiliary chamber 26 connected to the cylinder operation chamber 7 through the conduction hole 25 decreases during the opening operation to the open state, and the force for closing the valve is the minimum necessary. Therefore, no excessive stress acts on the valve seat 27, so that damage to the valve seat can be prevented. Further, if any abnormality occurs and the closing pilot valve 39 remains open even after the closing operation is completed, the secondary side remains at a high pressure.
Since the anti-pumping piston operating chamber 44 continues to leak to the low pressure side via 5, 46 and rises to the pressure determined by these throttles, the anti-pumping piston 42 moves to the left as in the closing operation shown in FIG. Check valve 41
And keep the circuit closed. When an open command is issued in this state, as shown in FIG.
The primary side has a high pressure state and the secondary side has a low pressure state. Even in this state, the anti-pumping piston 42 exerts a force acting from the anti-pumping piston operation chamber 44 side on the check valve 4 side.
Since it is configured to be larger than the force acting from the primary side of No. 1, the check valve 41 is kept closed. Therefore,
The opening operation is performed to reach the open state shown in FIG. 7, but even in this state, the check valve 41 is kept closed. Therefore, in this state, even if the closing command is issued and the closing pilot valve 39 is opened, the pressure of each part does not change at all, and the check valve 4
Since 1 is kept closed, the switching valve 13 cannot be switched to the closing operation state, so that the closing operation is not performed. That is, when an abnormality occurs in the closing pilot valve 39, the closing state is maintained as it is, and when the opening command is issued, the opening operation is performed, but once the opening is completed, the closing cannot be performed.
Therefore, it functions as an anti-pumping mechanism for preventing a malfunction accident in which the circuit is closed after the opening operation. Further, when the closing pilot valve 39 is kept open, it continues to leak to the low pressure side via the throttles 45 and 46, so that the outflow of the high-pressure working fluid accumulated in the accumulator 9 increases, and the fluid pressure source Since the number of times of operation 8 increases, an abnormality can be detected by detecting this. Further, in the closed state, the piston 21 of the closing main valve 12 moves downward at a pressure higher than the pressure at which the pressure of the cylinder operating chamber 7 drops and the piston 5 starts to perform the opening operation. If the dimensions are set so that the main valve 12 is pushed open, the high pressure is supplied from the closing main valve 12 before the piston 5 starts the opening operation. For example, leakage occurs from the opening main valve 11. However, it is possible to prevent an erroneous operation in which the opening operation is performed without permission. In the open state, the dimensions are set so that the main valve 11 for opening is opened at a pressure lower than the pressure at which the pressure of the cylinder operating chamber 7 rises and the piston 5 starts closing operation. For example, since the opening main valve 11 is opened before the piston 5 starts the closing operation and the pressure is prevented from rising, even if a leak occurs from the closing main valve 12, the erroneous operation of the closing operation is prevented. it can. Further, since the switching valve pilot chamber 28 is connected to the control port 14 via the throttle 35, the switching valve 13 is slightly different from the opening pilot valve 37, the closing pilot valve 39, the check valve 41 and the like. Is maintained at the same pressure as the control port 14 which has already been switched, there is no erroneous switching operation. As described above, according to the present embodiment, the fluid pressure driving device can be downsized and its manufacture can be facilitated, malfunction can be prevented, and high reliability can be maintained for a long time. Is improved. Incidentally, as shown in FIG.
The valve body 20 and the piston 21 may be integrated into a valve body 20a, and the spring 23 may be omitted. Even with such a configuration, the piston 21 does not move away from the valve body 20 during the opening operation shown in FIG.
Only the valve remains closed, and the progress of the open operation remains unchanged. As described above, according to the present invention, since the pilot flow rate can be reduced, the valves such as the switching valve and the pilot valve as well as the fluid pressure driving device as a whole can be reduced in size and easily manufactured. In addition, stable characteristics can be obtained, damage and leakage of the valve seat can be prevented, and high reliability can be secured for a long period of time. Therefore, the reliability of the power supply system can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side sectional view showing a closed state of a circuit breaker according to one embodiment of the present invention. FIG. 2 is a side sectional view showing a state during the opening operation of FIG. 1; FIG. 3 is a side sectional view showing an open state from the end of the opening operation of FIG. 1; FIG. 4 is a side sectional view showing an initial state during the closing operation of FIG. 1; FIG. 5 is a side sectional view showing a later state during the closing operation of FIG. 1; FIG. 6 is a side sectional view showing a state where the closing pilot valve of FIG. 1 is in the middle of performing an opening operation from a state in which the pilot valve remains open; FIG. 7 is a side sectional view showing an open state after the closing operation of the closing pilot valve of FIG. 1 has been performed from an open state; FIG. 8 is a side sectional view showing a closed state of a circuit breaker according to a modification of the embodiment of FIG. 1; [Description of Signs] 11: Main valve for opening, 12: Main valve for closing, 13: Switching valve,
17: Opening main valve pilot chamber, 18: Low pressure chamber, 24:
Closing main valve pilot chamber, 25: conduction hole, 26: auxiliary chamber, 37: opening pilot valve, 39, closing pilot valve.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Goro Daimon 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Inside Hitachi Kokubu Plant (72) Inventor Yasuhide Takeda 1-1-1 Kokubuncho, Hitachi City, Ibaraki Prefecture No. 1 Hitachi, Ltd. Kokubu Plant (72) Inventor Hideo Kawamoto 1-1-1, Kokubun-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Kokubu Plant (56) References JP-A-6-338241 ( JP, A) JP-A-58-119119 (JP, A) JP-A-61-162677 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01H 33/30

Claims (1)

(57) Claims: 1. A hydraulic cylinder for opening and closing a contact, a main valve for opening or closing the hydraulic cylinder, and an open or closed operation state of the main valve. A switching valve, a pilot valve for switching the switching valve between an open circuit operation state and a closed circuit operation state in response to an open circuit command or a close circuit command, a fluid pressure source for pressurizing and supplying working fluid, and pressurizing from the fluid pressure source. In a fluid pressure drive device of a circuit breaker provided with an accumulator for accumulating the supplied working fluid and a reservoir for collecting and storing the discharged working fluid, the fluid pressure cylinder is always located in a room having a smaller pressure receiving area. The supply pressure is applied, the operation chamber having a large pressure receiving area is operated to open at a low pressure, and the operation chamber is operated to close at a high pressure. The main valve returns the operation chamber of the fluid pressure cylinder to the open state. The main valve for opening and connecting to the supply side and the main valve for connecting and closing the operation chamber of the fluid pressure cylinder to the supply side are provided separately, while the switching valve is provided for the main circuit for opening. An opening valve for operating a valve and a closing valve for operating the closing main valve are integrally formed, and the opening main valve is connected to a back side of a valve body and to a return side by an opening valve of the switching valve. When the pressure is reduced to a low pressure, the opening main valve is opened, and the switching valve is connected to the supply side by a closing valve to close the opening main valve when the pressure becomes high. A low-pressure chamber disposed in the same direction as the chamber and always connected to the return side; and a spring for applying a force for closing the open-circuit main valve, while the close-circuit main valve is connected to the supply side by the switching valve. When the pressure rises to a high pressure, the closing main valve is opened and the return side is connected. A closing main valve pilot chamber that closes the closing main valve when the pressure becomes low and a spring that applies a force to close the closing main valve, and an auxiliary chamber that is connected to an operation chamber of the fluid pressure cylinder. The switching valve is connected to an output port of the pilot valve, and when the pressure becomes high, the switching valve is switched to a closing operation state, so that the switching valve is closed. And a switching valve pilot chamber for switching the switching valve to an open circuit operation state.